The Region Encoded by the Alternatively Spliced Exon IIIA in Mesenchymal Fibronectin Appears Essential for Chondrogenesis at the Level of Cellular Condensation

Fibronectin in the extracellular matrix of tissues acts as a substrate for cell adhesion and migration during development. Heterogeneity in the structure of fibronectin is largely due to the alternative splicing of at least three exons (IIIB, IIIA, and V) during processing of a single primary transc...

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Bibliographic Details
Published in:Developmental biology 1997-10, Vol.190 (2), p.191-205
Main Authors: Gehris, Amy L., Stringa, Emanuela, Spina, Joseph, Desmond, Mary E., Tuan, Rocky S., Bennett, Vickie D.
Format: Article
Language:English
Subjects:
Alternative Splicing
Animals
Cartilage - cytology
Cartilage - embryology
Cell Aggregation
Cells, Cultured
Chick Embryo
Exons
Extremities - embryology
Fibronectins - genetics
Fibronectins - immunology
Immunohistochemistry
Limb Buds
Mesoderm
Peptide Fragments - immunology
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Summary:Fibronectin in the extracellular matrix of tissues acts as a substrate for cell adhesion and migration during development. Heterogeneity in the structure of fibronectin is largely due to the alternative splicing of at least three exons (IIIB, IIIA, and V) during processing of a single primary transcript. Fibronectin mRNA alternative splicing patterns change from B+A+V+ to B+A−V+ during chondrogenesis. In this report, immunohistochemical analysis demonstrates that while fibronectin protein containing the region encoded by exon IIIB is present throughout the limb at all stages of development, fibronectin protein containing the region encoded by exon IIIA disappears from cartilaginous regions just after condensationin vivoand in high-density mesenchymal micromass culturesin vitro.Treatment of mesenchymal micromass cultures prior to condensation with an antibody specific for the region encoded by exon IIIA disrupts the formation of cellular condensations and inhibits subsequent chondrogenesis in a dose- and time-dependent manner. Furthermore, microinjection of the exon IIIA antibody into embryonic chick limb primordiain vivoresults in malformations characterized by smaller limbs and loss of limb skeletal elements. These results strongly suggest that the presence of the region encoded by exon IIIA in mesenchymal fibronectin is necessary for the condensation event that occurs during chondrogenesis.
ISSN:0012-1606
1095-564X
DOI:10.1006/dbio.1997.8693